The prior art discloses E-64 (U.S. Pat. No. 3,911,111), its intermediates [Chemical Abstracts, 87, 202108y (1977), ibid., 87, 85238c (1977), ibid., 87, 202125b (1977), ibid., 87, 68128z (1977)], and epoxy-succinic acid derivatives of German Patent Application Laying Open No. P 28 09 036 and Chemical Abstracts, 87, 68129a (1977) prepared by several of the present inventors.
The compounds of the present invention are distinguished from the prior art compounds by inhibitory activity to calcium-activated neutral thiolprotease (hereafter abbreviated as CANP) which exists in excess in muscle of muscular dystrophy mammals, and by good absorption and distribution in tissues after administration to mammals without acceleration of vascular permeability.